/*
 * Copyright (C) 2018 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.RegularImmutableMap.makeImmutable;
import static java.util.Objects.requireNonNull;

import com.google.common.annotations.GwtCompatible;

import java.util.Map;
import java.util.function.BiConsumer;
import javax.annotation.CheckForNull;

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of ImmutableMap backed by a JDK HashMap, which has smartness protecting against
 * hash flooding.
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class JdkBackedImmutableMap<K, V> extends ImmutableMap<K, V>
{
    /**
     * Creates an {@code ImmutableMap} backed by a JDK HashMap. Used when probable hash flooding is
     * detected. This implementation may replace the entries in entryArray with its own entry objects
     * (though they will have the same key/value contents), and will take ownership of entryArray.
     */
    static <K, V> ImmutableMap<K, V> create(int n, @Nullable Entry<K, V>[] entryArray)
    {
        Map<K, V> delegateMap = Maps.newHashMapWithExpectedSize(n);
        for (int i = 0; i < n; i++)
        {
            // requireNonNull is safe because the first `n` elements have been filled in.
            entryArray[i] = makeImmutable(requireNonNull(entryArray[i]));
            V oldValue = delegateMap.putIfAbsent(entryArray[i].getKey(), entryArray[i].getValue());
            if (oldValue != null)
            {
                throw conflictException("key", entryArray[i], entryArray[i].getKey() + "=" + oldValue);
            }
        }
        return new JdkBackedImmutableMap<>(delegateMap, ImmutableList.asImmutableList(entryArray, n));
    }

    private final transient Map<K, V> delegateMap;
    private final transient ImmutableList<Entry<K, V>> entries;

    JdkBackedImmutableMap(Map<K, V> delegateMap, ImmutableList<Entry<K, V>> entries)
    {
        this.delegateMap = delegateMap;
        this.entries = entries;
    }

    @Override
    public int size()
    {
        return entries.size();
    }

    @Override
    @CheckForNull
    public V get(@CheckForNull Object key)
    {
        return delegateMap.get(key);
    }

    @Override
    ImmutableSet<Entry<K, V>> createEntrySet()
    {
        return new ImmutableMapEntrySet.RegularEntrySet<>(this, entries);
    }

    @Override
    public void forEach(BiConsumer<? super K, ? super V> action)
    {
        checkNotNull(action);
        entries.forEach(e -> action.accept(e.getKey(), e.getValue()));
    }

    @Override
    ImmutableSet<K> createKeySet()
    {
        return new ImmutableMapKeySet<>(this);
    }

    @Override
    ImmutableCollection<V> createValues()
    {
        return new ImmutableMapValues<>(this);
    }

    @Override
    boolean isPartialView()
    {
        return false;
    }
}
